Select Committee on Science and Technology Appendices to the Minutes of Evidence


Memorandum submitted by Tidal Electric Ltd


  1.  Tidal Electric Ltd (TE) is currently developing three1 tidal power plants in the UK using its new technological approach to tidal power generation2. These projects will be the first-ever embodiments of the offshore impoundment structure approach to tidal power. The UK has very large tidal ranges and many suitable sites for further installations that could conceivably generate thousands of megawatts.


  2.  TE's technology involves an offshore impoundment structure, segmented into three or more compartments and fitted with conventional low-head hydroelectric generating equipment. The equipment is commonly available from numerous manufacturers and it is a reliable mature technology that is capable of mechanical efficiencies in the 95 plus per cent range and is performance guaranteed by its manufacturers with a design life of 50 plus years. There are many thousands of similar turbine/generator sets currently installed in river applications. Similar bulb-type turbine/generator sets are in use at the LaRance Tidal Power Station in St Malo, France and these units have been in operation since 1965 and are only now beginning to show signs of age.

  3.  The impoundment structures will be built using conventional marine construction techniques. The most likely material to be used is locally obtained loose rock, sand and gravel, although other materials may be used, if circumstances require. The impoundment structure will be segmented into separate cells in order to provide flexibility to the operator to optimise generation by phasing output from each of the cells. TE has developed a computer simulation model with which various generation schemes can be simulated, optimised and studied. The simulation model has achieved a load factor of 62 per cent and output can be generated 81 per cent of the time.

  4.  The oceans' tides are highly variable but precisely predictable using mathematical formulae that can calculate tidal behaviour as far into the future as required. Similarly, the hydroelectric generating equipment is mature and its output efficiencies are known throughout its head range.3 Using British Admiralty tidal data, the output from the tidal generator is predictable down to 6-minute increments for as far into the future as desired. Predictability of output is important when integrating the output into a grid system and lack of predictability has been a drawback for other sources of renewable power.


  5.  TE's technology has never been built before and bears the inherent risks of unsuspected problems arising despite thoroughgoing engineering planning. In order to consider investing in such a venture, a private investor must see sufficient return to absorb potential cost overruns, operational problems, and other unpredicted negative events. The value of the Renewables Obligation Certificate (ROC) provides that extra revenue and is the key to attacting investors. Without the ROC, TE's technology would require some form of grant and/or subsidy support to achieve competitiveness. With the ROC, TE's technology is apparently competitive. TE's technology, together with the ROC, has proven itself sufficiently promising to attract private investment on each of its three proposed projects.4 Other investors have expressed interest in future projects. The only apparent remaining potential roadblock to commercial viability is the consents process. Careful monitoring of the initial projects will indicate the accuracy of projections and actual performance will determine whether future projects would be competitive.


  6.  TE's technology has the potential to make significant contributions to helping the Government reach its targets for greenhouse gas emissions reduction. The ROC and the Renewables Obligations on electricity providers creates enough assistance to make initial projects commercially attractive to private investors. Thus, while the existing support is critical to the viability of TE's contribution to renewables in the UK, no further assistance is required at this point. Therefore, we suggest that tidal power need not be a higher priority, just as long as it does not become a lower priority. Should preliminary cost projections prove to be significantly underestimated, TE's technology could require further grant or subsidy assistance.


  7.  All research and development of TE's technology is currently funded privately. Focus is on the three active projects in Wales and studies are being planned and initiated as necessary preconditions for filing Planning Applications for the three projects. TE may apply for public funds to support its research and development activities at some point in the future, but its near-term needs are being met with private funds.


  8.  The installation of a tidal generator will impact its surrounding area by changing the behaviour of currents and waves, which will, in turn, change existing sediment transport regimes. It will be important to build sediment transport models that will dictate design parameters to designers so that the structure will not deposit more sediment in shipping channels or increase the removal of beach sands. ABP Research Ltd has been engaged to undertake such studies for the Swansea Bay Project. It is expected that their considerable expertise in the field of sediment transport modeling, combined with the fact that ABP owns the ports of Swansea and Port Talbot, will produce a carefully crafted design that does not disrupt the sediment transport regime of Swansea Bay. Similar efforts will take place for the other two projects.

  9.  The impoundment structure for the tidal generator will be constructed of locally obtained loose rock, sand and gravel and it will have a natural appearance, similar to existing shoreline coastal defense projects. Upon construction, the impoundment structure will quickly become a habitat for many species from micro-organisms on up through the food chain. It will provide nesting habitats for the avian community and it is expected that it will increase biodiversity in the area and provide a safer habitat for some of the endangered species in the area. Careful and complete studies of the environmental impact will be conducted prior to Planning Application, throughout construction, and during operations, so that future projects can be guided by the experience of these initial projects. The projects have already created considerable interest in the academic environmental community at such institutions as the University of Wales (Bangor) Institute for the Environment. It is expected that the projects will become focal locations for many academic research studies.

  10.  The operation of the turbines will create some localised turbulence. Mature fish can sense the underwater pressure wave that the turbulence creates and will avoid the area. An occasional fish will be swept through the turbines and 94 per cent of these unlucky few will survive. It should be noted that this is a very different situation from a conventional dam across a river that anadromous5 fish must navigate, first when outmigrating and again when they return to spawn. Every one of these fish must pass through the turbines twice. While mortality rates are the same whether the turbine is in a dam across a river or in the tidal generator, far fewer fish will go through the tidal generator's turbines and fish mortality will be orders of magnitude lower for the tidal generator.

  11.  The tidal generator will be sited in shallow water because its power source is the difference in water levels caused by the tides and all its power is located between high tide and low tide. Any construction below low tide is merely for the purpose of supporting that part of the structure that is above low tide and, therefore, it is an unproductive expense and will be minimised. Shipping lanes require the greatest depth available and, therefore, the tidal generator and the shipping lanes are unlikely to be in the same place. However, the tidal generator's impoundment structure will be fitted with suitable nautical warning devices.

  12.  The North Wales coastline is hostile to pleasure boats because of its high tides and strong wind and wave regime. The installation of a tidal generator impoundment structure is being hailed by local boatmen as a boon to their business in that it will create a large area of calm water in which pleasure boats can moor and marinas can operate.


  13.  The UK is the sole location under consideration for TE's tidal generation technology. This is due to the fact that the UK has very large tidal ranges, it is densely populated, and the Government has created ROC's to enhance the economics of renewable technologies. Given a successful start in the UK, TE expects to broaden its deployment of its technology to many high tidal range areas of the world.


Fifoots Point Tidal Power Plant

  14.  In April 2000, TE and AES Electrical Ltd (a subsidiary of AES Inc, the world's largest independent power producer) signed an agreement under which a 30 MW tidal power project will be developed near Fifoots Point in the Bristol Channel of the Severn Estuary. AES owns a 360 MW coal-fired power station at Fifoots Point and the two power plants will share management staff, facilities, and a 400 MW grid connection.

  15.  The first phase of the engineering studies is underway: Harza Engineering is adapting the Tidal Power Generation Simulation Model (intially built to model TE's tidal power project in Alaska) to the tides in the area of Fifoots Point. Harza has run two potential configurations and is working on a third. Each "run" involves the virtual operation of the system, complete with mechanical losses, using the tidal predictions at six-minute increments for the year 2003. The output is an accurate calculation of generation totals and instantaneous output, thereby giving enough data to refine the configuration.

  16.  After defining an output curve, the development team will issue an RFP for the power and determine what price can be expected and thereby determining the project economics. The engineering team will be chosen and studies will commence. It is expected that the studies will take six months to complete and a Planning Application will then be submitted to the DTI. Planning Approval could be reasonably expected within six to 18 months, whereupon construction can commence.

  17.  The construction of a tidal power plant is divided into civil works and equipment manufacture. The equipment will be manufactured by a turnkey contractor such as ABB or GE and is estimated to take about 16 to 18 months. The civil works schedule is planned to take two years in order that the two components might finish at roughly the same time. There is considerable flexibility in the civil works scheduling as the amounts of material required per day are well within the capacity of several potential suppliers, such as Hanson Aggregates. There has been discussion of using ash from the Fifoots coal power station, slate waste, steel slag, and other "waste" type materials that presumably would be less expensive. TE has recruited the RSPB to assess the potential impacts of the use of these materials and the economics of using these materials would have to be compelling for them to be included in the design. Assuming a one-year timetable until Planning Approval and a two-years construction schedule, the Fifoots Tidal Power Project could be in service in mid-2004, but a more conservative would be 2005.

Swansea Bay Tidal Power Plant

  18.  TE has an agreement to develop a 30 MW tidal power plant in Swansea Bay (Wales) in co-operation with the Environment Trust (, a non-profit charitable trust that believes in the community ownership of utilities. Most recently, the Environment Trust was responsible for the renovation and development of Mile End Park in the East End of London, a complex and multi-faceted project that involved the local community on a ground floor planning level.

North Wales Tidal Power Project

  19.  The coastline of North Wales has been fighting a losing battle with erosion for centuries. Rising ocean levels and global climate change have sped this process and the people of North Wales feel justifiably threatened by the Irish Sea and its relentless march inland. TE has been working with a consortium of political and environmental groups in North Wales in order to identify and conceptualise a tidal power project that will be configured in such a manner as to help resist the forces of erosion and the periodic flooding that has devastated the area, most notably in the so-called Towyn Floods of 1990. Such a configuration will provide 432 MW of power and provide coastal defence along the vulnerable area.

  20.  A core group of supporters has been identified for the North Wales Project, including a local county councillor, a Friends of the Earth campaigner, a wind power developer, the Mayor of one of the local villages, and TE CEO Peter Ullman. This group is exploring the various possible secondary on-shore projects that will enhance the tidal power project. The tidal power plant in France gets 600,000 visitors per year and the North Wales group is anticipating an increase in the tourist traffic from visitors to the tidal power plant. They are eager to add attractions such as a sea-life museum, an education centre, and the like. Transportation and housing are also of concern to the planning group.

  21.  TE is in advanced discussions with Conoco Global Power Ltd and it is anticipated that a Joint Development Agreement will be signed in March, 2001, and the joint venture will develop the North Wales project.


  1  Swansea Bay (30 MW), Fifoots Point (30 MW), North Wales (432 MW).

  2  TE has expertise regarding its technology, but claims no expertise in wave power, tidal stream (marine currents) technology, or barrage tidal power. Therefore, evidence will be limited to its area of expertise.

  3  Hydroelectric generating equipment operates by allowing water at different levels to pass through and turn its turbine runner. Head Range is a range of water levels (head) through which it operates. Each point in that range has a differing mechanical efficiency, due to the differing amount of pressure.

  4  Fifoots Point (AES Electric Ltd), Swansea Bay (Environment Trust Associates Ltd), and North Wales (Conoco Global Power Ltd in negotiation, expected signing in March, 2001).

  5  Anadromous fish, like salmon and smelts, live part of their lives in fresh water and part of their lives in salt water and must go from one habitat to the other or die trying.

8 February 2001

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